NDA (II) 2023 General Ability Test · Question 71 of 146

Correct — B, Pollination. The bee comes for food, not for the flower's benefit — it collects nectar and pollen. While it works the flower, pollen grains stick to the hairs on its body, and it carries them to the next flower it visits, where some rub off on the stigma. That transfer of pollen from anther to stigma is pollination, and for a rooted plant that cannot move, an insect courier is the whole point of the relationship. Each side gains something, so this is a classic case of mutualism.

• (a)Faster development — A bee has no effect on how fast the plant grows. It visits a flower only after the flower has already developed and opened, so it cannot be speeding that development up.
• (c)Quick germination of pollen — A pollen grain germinates once it lands on a compatible stigma and responds to the stigma's secretions. The bee's contribution ends with delivering the grain to the right address; it does not make the grain sprout faster.
• (d)Increase in size — The size of a flower is set by the plant's own growth and its genes. What does enlarge later is the ovary as it ripens into a fruit, and that happens after fertilisation — it is a downstream result, not what the bee does for the flower.

Pollination is the transfer of pollen grains from the anther to the stigma, and it must happen before fertilisation can. Plants that cannot move rely on carriers — wind, water, insects, birds or bats. Pollination by insects is called entomophily, and bees are the most important insect pollinators. The flower pays for the service in nectar and surplus pollen, so both partners benefit and the association is mutualistic.

The stem asks what the flower gains, so eliminate anything the bee physically cannot do. It cannot make a plant grow faster, cannot enlarge a flower, and cannot trigger a pollen grain to germinate — germination is the stigma's business. What it can do is move pollen between flowers, and that single service is the reason insect-pollinated flowers evolved colour, scent and nectar in the first place. Cross-pollination also brings in pollen from a different plant, which is where the genetic variation comes from.

• Pollination is the transfer of pollen from anther to stigma; fertilisation can only follow after it.
• Pollination by insects is called entomophily, and honey-bees are among the most effective insect pollinators.
• Insect-pollinated flowers typically offer nectar and carry sticky pollen that clings to a visitor's body.
• The flower-and-bee association is mutualism — the bee takes food, the plant gets its pollen carried to another flower.

• Confusing pollination with fertilisation — the bee delivers the pollen, it does not fuse the gametes.
• Reading the ripening of the ovary into a fruit as the flower itself increasing in size.
• Assuming the bee visits in order to help the plant, when it visits for its own food.

Asked as a plain 'what does the pollinator do' item, as an ecological-interaction item on mutualism, or as an environment item on the consequences of pollinator decline.

• practice — not a real PYQ

  Pollination brought about by insects is termed

  • (a)anemophily
  • (b)hydrophily
  • (c)entomophily
  • (d)ornithophily

  Answer(c) entomophily — pollination by insects; anemophily is by wind, hydrophily by water and ornithophily by birds.

• practice — not a real PYQ

  The association between a flowering plant and its insect pollinator is best described as

  • (a)parasitism
  • (b)mutualism
  • (c)commensalism
  • (d)predation

  Answer(b) mutualism — the insect gains food and the plant gains pollen transfer, so both benefit.